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Activation of primary T lymphocytes results in lysosome development and polarized granule exocytosis in CD4 + and CD8 + subsets, whereas expression of lytic molecules confers cytotoxicity to CD8 + T cells
Author(s) -
Shen David T.,
Ma Jennifer S. Y.,
Mather Jacques,
Vukmanovic Stanislav,
Radoja Sasa
Publication year - 2006
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.0603298
Subject(s) - biology , exocytosis , lytic cycle , microbiology and biotechnology , cytotoxic t cell , lysosome , granule (geology) , cd8 , cytotoxicity , t lymphocyte , immunological synapse , immunology , t cell , immune system , membrane , biochemistry , in vitro , enzyme , t cell receptor , virus , paleontology
Lytic granule exocytosis is the major cytotoxic mechanism used by CD8 + cytotoxic lymphocytes. CD8 + T cells acquire this effector function in the process characterized by lysosomal biogenesis, induction of expression of cytolytic molecules, and their selective sorting into the lysosomal vesicles. However, temporal relation of these differentiation stages during T cell activation has not been defined precisely. Also, although CD4 + T cells typically do not express lytic molecules as a consequence of activation, and therefore, do not acquire granule exocytosis‐mediated lytic function, it is not clear whether CD4 + T cells are able to degranulate. By using in vitro TCR stimulation of primary mouse lymphocytes, we found that polyclonally activated CD4 + T cells degranulate upon TCR ligation and polarize enlarged lysosomal granules in response to target cell recognition, despite the lack of granule exocytosis‐mediated cytotoxicity. Upon TCR stimulation, resting CD8 + T cells rapidly express lytic molecules and acquire potent lytic function early in activation. Maximal cytolytic potential, however, depends on enlargement of lysosomal granules during the subsequent activation stages. Thus, polyclonal TCR stimulation of resting T cells results in development of lysosomal granules and their release upon TCR engagement in CD4 + and CD8 + T cells, but only CD8 + T cells acquire lytic function as a result of induction of expression of lytic molecules.